If we except a short excursion down the Blackwood and Kojonup Rivers, his expedition of 1846, in which he was accompanied both by F.T. and H.C. Gregory, was the first important enterprise undertaken by him. It was in August that his party left Captain Scully's station at Bolgart's Springs, about seventy miles from Perth. On leaving the settled districts they at once found themselves in the barren country that was damming back the eastward flow of settlement. Having traversed it, they reached a range of granite hills, and turning more to the northward, they kept along these for the sake of the rain-water to be found in the rock holes. On striking again to the east, they encountered an extensive salt lake, and in attempting to cross an arm of this marsh, their horses were bogged, and extricated only after great labour. The lake was afterwards proved to be of great size, and to hem them in completely to the eastward, whilst, owing to its crescent-like formation, for five days it baffled all their attempts to proceed northwards. Finally abandoning the lake, which they called Lake Moore, they turned to the westward to examine some of the streams crossed by Grey during his return from Shark's Bay. On the head of one of these rivers, the Irwin, they found a seam of coal. "Having pitched our tent and tethered our horses, we commenced to collect specimens of the various strata, and succeeded in cutting out five or six hundredweight of coal with the tomahawk, and in a short time had the satisfaction of seeing the first fire of West Australian coal burning cheerfully in front of the camp, this being the first discovery of coal in Western Australia." The party then returned by way of the Moore River to Bolgart Springs, which they reached on the 22nd of September. The discovery of coal deposits and of country available for settlement was seen to be of great importance by the Government, and Lieutenant Helpman, A.C. Gregory, his brother Henry, and Messrs. Irby and Meekleham, in the colonial schooner Champion, were despatched to procure a quantity of coal for testing. They were also instructed to make a further inspection of the pastoral capabilities of the district, of which there had been so many conflicting opinions. A three days' examination of the country convinced them that it was suitable for settlement. In 1846 Gregory took charge of an expedition to the north of Perth, organised by the settlers of the colony, and entitled The Settlers' Expedition; its object being to proceed to the Gascoyne River, examining the intervening country as to its suitability for pastoral purposes.